On the Mac OS X you browse your files and folders using Finder, which hides all hidden folder and files. To view these hidden files and folders in finder open a Terminal window and type the following command:

defaults write com.apple.finder AppleShowAllFiles -bool true

To hide the hidden files again in Finder simply execute the same command with the boolean value changed from ‘true’ to ‘false’.

To block advertisements on your Mac OS X, add domain name mappings to your local /private/etc/host file. See for more details:
http://www.mindxp.com/2006/04/08/filtering-ads-while-browsing/.